For various economic and business reasons enterprises are increasingly centralizing their backend computer systems in purpose built data centers. Data centers typically house high concentrations and densities of such computer systems and additionally provide facilities such as uninterruptible power supplies and cooling systems necessary for the operation of the computer systems in the data center.
Computer systems inherently generate heat during operation. Typical heat generating sources in a computer system include central processing units (CPUs), graphics cards, mechanical storage drives, power supplies, and the like. This heat needs to be managed such that the maximum operating temperature of the various components of each computer system is not exceeded.
Individual computer systems, such as servers, typically use heat sinks to remove heat from heat generating sources. The heat is then evacuated outside the computer system housing by one or more internal mechanical fans which draw in cooler air from outside the computer system housing and exhaust warmed air through an exhaust vent. Typically computer systems are designed to draw air in through a vent on the front of the system and to exhaust warmed air through a vent in the rear of the system.
When arranged in data centers, computer equipment is generally installed in a frame or enclosure, such as a server enclosure rack, a rackable cabinet, or a server rack. Hereinafter structures suitable for housing computer equipment are referred to as equipment enclosures. An equipment enclosure may house multiple items of computer equipment. Generally the depth of the equipment enclosure is chosen to have the approximately the same depth as the computer equipment installed therein. The rear panels of equipment enclosures are generally either not present, or are perforated to enable suitable ventilation of the installed computer equipment. In this way, air from outside the equipment enclosure is drawn into the computer equipment through a computer equipment front inlet vent, and is exhausted out of the computer equipment through a computer equipment rear exhaust vent. In such an arrangement, outside air heated by the computer equipment does not enter the equipment enclosure.
Data centers also generally use computer room air conditioning units that supply cooled air to the front of the equipment enclosures and evacuate heated air from the back of the equipment enclosures to enhance cooling of the computer equipment.
Accordingly, a significant proportion of the operating cost of a data center can come arise from the operation of cooling systems, both within individual computer equipment and at the data center infrastructure level